Process of manufacturing electrical contact members



FYLJGH May 9 193.30

PROCESS OF MANUFACTURING ELECTRICAL CONTACT MEMBERS Filed Nov. 24, 1930Patented May 9, v 1933 UNITED STATES Parent EMERSON" PU'GE, 0F DOWNERSGROVE, ILLINQIS, ASSIGNUR T63 WESTERN EEECTRIG COMPANY, INCORPORATED,015 NEW YORK, N. Y., i-l CGRPORATIQN OF NEW YORK PROCESSOF MANUFACTURINGFLJECTRIGAL CONTACT TQEMBERS Application filed November 24, 1930. SerialNo. 497,784,

This invention relates to aprocess of manmetal with the sections ofcontact metal se ufacturing electrical contact members, and

more particularly to a process of manufacturing bimetallic contactelements.

It is an object of the present invention to provide an efficient processof manufacturmg composite bimetallic, electrical contacts, utilizing aminimum amount of contact metal.

In accordance with one embodiment, the invention contemplates a processof manufacturing bimetallic contact elements wherein contact metal,suchas platinum, palladium or alloys of either of these metals with goldor other of the precious metals particularly adaptable for electricalcontact elements is formed into a substantially cylindrical strip orwire having a ridge longitudinally thereof, may be cut to predeterminedlengths, and then welded to a base metal such as nickel silver, purenickel or other metals having a high degree of resistance to corrosionat spaced intervals, which is formed in a strip or ribbon ofsubstantially rectangular cross-section,

v and which is provided with two ridges extending longitudinallythereof. By having the longitudinal ridge on the wire of contact -metal,the current applied for welding purposes to the elements making up thecomposite contact is localized at the point of contact between thecontact wire and the ribbon of base metal thereby insuring a strongwelded union and avoiding the possibility of damaging the contact wireor base metal by the heat of the current required to form the weld. A

- composite contact element thus formed may then be secured to a contactspring of electrical apparatus by welding the base metal weldingoperation Fig. 2 is a plan view of the ribbon of base tion of thecontact elements thereon in their completed form.

Referring now to the drawing wherein the same reference charactersdesignate like parts throughout the several views, the numeral 6indicates a strip or wire of precious metal of the type commonly usedfor contact metal in the contacts of electrical apparatus and is formedto a substantially circular cross-section having a rounded ridge 8extending longitudinally thereof. After the wire 6 of contact metal hasbeen formed to the above described shape, it is cut into predeterminedlengths and combined, as shown in Fig. 2, with a strip 10 of base metalwhich may be nickel silver, pure nickel or other metals which have ahigh degree of resistance to corrosion, being positioned upon the basemetal at spaced intervals with the ridge 8 of the wire 6 engaging theflat upper surface of the strip 10 which is substantially rectangular incross-section and which has depending ridges 12 extending longitudinallythereof.

The wire 6 of contact metal and the strip 10 of base metal are showninFig. 1 engaged by electrodes '14 and. 16 electrically connected with asource of current supply 15 so that an electrical welding circuit may becompleted through the electrode 14:, the wire 6 of contact metal and thestrip 10 of base metal to the electrode 16 to weld the contact metal tothe base metal. The electrode 14 engages that portion of the wire 6 awayfrom the ridge 8, and the electrode 16 engages the under side of thebase metal. Therefore, a welding current passing through the wire ofcontact metal and the strip of base metal will encounter its greatestresistance at the line of engagement of the ridge 8 with the flat uppersurface of the strip 10, and due to the formation of the wire 6 theelectrode 14 engages therewith over a comparatively large area, whereasthe ridge 8 provides only a small area of contact with the base metal,thereby resulting in a concentration of the welding current along theline of contact. This concentration of the welding current will causefusion of the contact metal and the base metal strip 10 and will preventthe base metal from sticking to the electrode 16 or from burning due tothe fact that the relatively large crosssection of the base metalprovides a chilling effect at the point of contact with the preciousmetal and causes the ridge of the contact metal which has a relativelysmall crosssection to rise to the melting temperature at'approximatelythe same time that the base metal is raised to its melting temperature,thus permitting an intimate mixture of the molten metals and a strongweld.

After the wire 6 of contact metal has been formed to the shape .shown inFig. 1, cut to predetermined lengths and welded to the strip 10 of basemetal at intervals along the length thereof, as shown in Fig. 2, in themanner described hereinbefore, the composite contact elements thusformed may be out along the lines 18, 20, and 22 to provide separatecomposite contact elements 23 which may be attached to contact springs24 of electrical apparatus.

Referring now to Fig. 3, a composite contact element 23 cut from thestrip as just described may be positioned at an angle of approximately45 upon a flat surface of an electrical contact spring 24 with theridges 12 engaging the upper surface of the spring. A welding electrode26 may be engaged with the flat upper surface of the strip of base metal10 and a welding electrode 28 having a polarity opposite to that of thewelding electrode 26 may be engaged with the underside of the contactspring to complete a weldng circuit which may be the same as shown 1nFig. 1 through the electrode 28, contact spring 24, base metal strip 10to the welding electrode 26. This welding circuit may be maintaineduntil the downwardly extending ridges 12 of the strip 10 have fused withthe upper surface of the contact "spring 24 to secure the compositecontact element to the spring 24 as shown in Fig. 4. The'provision y ofthe downwardly extending ridges 12 on the strip 10 of the base metalprovides concentration points for the welding current applied to thebase metal and the electrical contact spring so that despite thedifference in the fusing temperatures of the metal of the strip 12 andof the contact spring, the fusion of these metals upon application ofthe welding current will occur substantially simultaneously, therebypreventing sticking of the metals to the welding electrodes or burningof the base metal and providing a good welded union between the twoparts.

Contact springs formed in accordance with the above outlined method maybe combined as shown in Fig. 5 wherein a pair of springs are shownhaving positioned near the ends thereof and upon opposing surfacesthereof, a pair of cooperating contact elements. The contact elementsare positioned diagonally of the springs and the element carried by onespringis angularly disposed with respect to the cooperating contactelement carried by the other or companion spring. By having thisarrangement a cross contact is effected between the adjacent surfaces ofthe two contact elements in response to movement of one of the springs,and it will be apparent that less precious metal is necessary than wouldbe required in the ordinary type of contact element since acomparatively large area is provided for use as contacting surface andeven if the associated springs 24 are not exactly aligned a contact willbe made between the contact elements upon operation of the springs.

Although a specific embodiment of the invention has been describedhereinbefore, it will be understood that modifications and adaptationsof the method may be made without departing from the scope of theinvention which is to be limited only by the appended claims.

What is claimed isi 1. The process of manufacturing bimetallic contactelements which includes forming a base metal to predetermineddimensions, forming a contact element of a higher melting point metalwith a depending rounded ridge adapted to engage the base metal, weldingthe contact metal to the base metal and welding the base metal to acontact spring.

2. The process of manufacturing bimetallic contact elements whichincludes forming a ribbon of base metal to a substantially rectangularshape having depending ridges on one portion thereof, forming a contactele-' ment of a higher melting point metal with a depending ridgeadapted to engage the base metal, combining the base metal and contactmetal with the depending ridges of the base metal on the side thereofaway from the contact metal, welding the contact metal to the basemetal, engaging the depending ridges of the base metal with a contactspring and welding the base metal to the contact spring.

3. The process of manufacturing bimetallic contact elements whichincludes forming a base metal with a depending ridge, forming a contactelement of a higher melting, point metal having a substantiallycylindrical cross-section with a protuberance on its periphery,contacting the base metal and contact metal with the protuberance of thelic contact elements which includes forming a ribbon of base metal ofpredetermined dinnensions, forming a contact element of a higher meltingpoint metal and having a substantially cylindrical cross-section with aprotuberance on its periphery, contacting the base metal and contactmetal with the protuberance of the contact metal engaging the basemetal, applying electrodes to the base metal and that portion of thecontact metal farthest removed from the protuberance, ap-

With a section of contact metal welded thereto in a position with theridges engaging a contact spring, applying a welding electrode to theupper surface of the composite base and contact metal, applying anotherwelding electrode to the underside of the contact spring, and completingan electrical circuit through the welding electrodes to weld thecombined contact and base metal to the contact spring. K

In witness whereof, I hereunto subscribe my name this 15th day ofNovember A. D.,

EMERSON PUGH.

plying a welding current to the electrodes to I fuse thebase metal and.contact metal at the point Where the protuberance of the contact a metalengages .the' base metal and welding \face thereof, cutting the contactmet-a1 into predetermined lengths, positioning the contact metal atintervals along the ribbon of base metal with the ridge of the contactmetal engaging the surface of the base metal opposite to the surface ofthe base metal on which the ridges are formed, applying weldingelectrodes to the base metal and to the surface of contact metal removedfrom the rounded ridge, applying a welding current to the electrodes toweld the contact metal to the base metal, cutting the/base metal withthe contact metal welded thereto to predetermined lengths, and weldingthe base metal to electrical contact springs.

6. The process of manufacturing bimetallic contact elements whichincludes forming a ribbon of base metal to a substantially rectangularcross-sectional shape having ridges on one surface thereof, forming awire of contact metal of ahigher melting point metal metal with therounded ridge formed on the contact metal engaging-the surface of thebase metal away from the ridges formed thereon, applying weldingelectrodes to' the v base metal and to the surface of the lengths ofcontact metal away from the ridge thereon, applying a welding current tothe electrodes to weld the contact metal to the base metal, cutting thebase metal with the contact metal welded. thereto to predeterminedlengths, positioning the length of base metal

